Endocrine Abstracts

Background: Diagnosing GDH in children remains matter of debate due to variability in results obtained with pharmacological tests, one child may fail one test, but pass another. Spontaneous GH secretion assessment is costly, time consuming, and results may show poor correlations with those obtained with provocative tests. To add to diagnosic power of provocative tests, testing IGF-I and IGF-PB3 have been suggested. In recent years, however, the contribution of IGF-PB3 assay to diagnosis of GHD has been questioned ( ).

Objective: To evaluate the contribution of IGF-PB3 assay to the diagnosis of GHD.

Population and methods: Retrospective case study. Boys and girls aged 0–18 years who attended our Paediatric endocrinology clinic for short stature and/or follow-up post-irradiation, and had at least one provocation test for GH secretion assessment. We excluded those with hypothyroidism, Laron syndrome, severe malnutrition, chronic renal failure and liver failure.

Results: Fifty-eight children were enrolled and grouped according to results as GHD (+) (19 cases) and GDH (−) (39 cases). IGF-I and IGF-BP3 assay was carried out in 88% and 62% respectively, both groups were comparable for age, sex, BMI, target height, pubertal stage and bone age. There was a difference in maximum GH peak obtained between GDH (+) and GHD (−) groups (41.8 mUI/l±21.7 versus 11.5±5.9 mUI/l, P<0.00001, respectively). No difference was found between groups with regards to IGF-I Z-scores and IGF-BP3 Z-scores. There was, however a positive correlation between IGF-I Z-scores and IGF-BP3 Z-scores (r=0.50; P<0.0016).

Conclusions:
– IGF-BP3 assay contributes poorly to diagnosis of GHD, with 24% Sensitivity and 92% Specificity respectively.

– Due to lack reference values adjusted for age, sex, and pubertal stage, we do not recommend its routine use.